<form action="/manage/wxmenu/setImg" target="upIframe" enctype="multipart/form-data" id="upAdForm" method="post" style="padding:15px 30px 50px">

    <div class="f-unit">
        <label class="ui-label">选择图片：</label>
        <input type="file" name="upFile">
    </div>
</form>
<iframe style="border:none; display:none;" name="upIframe"></iframe>